His notable work includes co-discovering the much studied
flipped SU(5) scheme of unification, identifying the Barr–Zee diagram as an important source of electric
dipole moment for
basic particles such as the electron and neutron in many theories, and proposing the so-called Nelson–Barr mechanism as a solution to the
strong CP problem. He is the author of the article on "Grand Unified Theories" for the
Encyclopedia of Physics. Barr received his PhD in theoretical particle physics from Princeton University in 1978. Princeton awarded him the Charlotte Elizabeth Proctor Fellowship "for distinguished research." He went on to do research at the
University of Pennsylvania as a post-doctoral fellow (1978–1980), the
University of Washington as a research assistant professor (1980–1985), and
Brookhaven National Laboratory as an associate scientist (1985–1987), before joining the faculty of the University of Delaware in 1987. He was elected director of the
Bartol Research Institute of the University of Delaware in 2011. Barr, a practicing Catholic, writes and lectures frequently on the relation of
science and religion. From 2000 to 2017 he served on the Editorial Advisory Board or Advisory Council of the ecumenical religious intellectual journal
First Things, in which many of his articles and book reviews have appeared since 1995. His writing has also appeared in
Commonweal,
National Review,
Modern Age,
The Public Interest,
America,
The Wall Street Journal, and other publications. In 2002 he gave the
Erasmus Lecture, sponsored by the Institute on Religion and Public Life. In 2007 he was awarded the
Benemerenti Medal by
Pope Benedict XVI. In 2010 he was elected a member of the Academy of Catholic Theology. He is also president of the
Society of Catholic Scientists. == Public lectures ==